The quark loop correction to the single gluon component of the LCWF is displayed
in Fig. REF . In the massless limit, the diagram is UV divergent, giving rise to running of
the coupling (the \(N_f\)  term in the \(\beta \) -function), after standard dimensional regularization is applied [1]}.
While renormalization is straightforward in the massless case, the massive case turns out to be much more involved.
Most of this subsection is devoted to carefully carrying out the renormalization procedure, which requires introduction of
a mass-dependent counter term.
